According to an email I just received from Amazon, it looks like HTC accidentally sent some of its WM6-running Advantage units (X7501) out the door with pre-production software. Exactly how many devices were released prematurely is unclear, but the problem does not seem specific to Amazon’s inventory. Owners who purchased their Advantages from CompUSA, for example, have been complaining about several pieces of missing software and a splash screen showing the words "Test Only – Not for Sale."
Amazon is vague about what the pre-production software is missing, suggesting only that users who are "experiencing any problems or errors" should upgrade their firmware/software. Whether the update resolves or is even related to what CompUSA customers are experiencing is unknown.
Full email from Amazon below.